Vincristine

Identification

Name

Vincristine

Accession Number

DB00541 (APRD00495)

Type

Small Molecule

Groups

Approved, Investigational

Description

Vincristine is an antitumor vinca alkaloid isolated from Vinca Rosea. It is marketed under several brand names, many of which have different formulations such as Marqibo (liposomal injection) and Vincasar. Vincristine is indicated for the treatment of acute leukaemia, malignant lymphoma, Hodgkin's disease, acute erythraemia, and acute panmyelosis. vincristine sulfate is often chosen as part of polychemotherapy because of lack of significant bone–marrow suppression (at recommended doses) and of unique clinical toxicity (neuropathy).

Vincristine is a vinca alkaloid antineoplastic agent used as a treatment for various cancers including breast cancer, Hodgkin's disease, Kaposi's sarcoma, and testicular cancer. The vinca alkaloids are structurally similar compounds comprised of 2 multiringed units, vindoline and catharanthine. The vinca alkaloids have become clinically useful since the discovery of their antitumour properties in 1959. Initially, extracts of the periwinkle plant (Catharanthus roseus) were investigated because of putative hypoglycemic properties, but were noted to cause marrow suppression in rats and antileukemic effects in vitro. Vincristine binds to the microtubular proteins of the mitotic spindle, leading to crystallization of the microtubule and mitotic arrest or cell death. Vincristine has some immunosuppressant effect. The vinca alkaloids are considered to be cell cycle phase-specific.

Mechanism of action

The antitumor activity of Vincristine is thought to be due primarily to inhibition of mitosis at metaphase through its interaction with tubulin. Like other vinca alkaloids, Vincristine may also interfere with: 1) amino acid, cyclic AMP, and glutathione metabolism, 2) calmodulin-dependent Ca2+-transport ATPase activity, 3) cellular respiration, and 4) nucleic acid and lipid biosynthesis.

Within 15 to 30 minutes after injection, over 90% of the drug is distributed from the blood into tissue, where it remains tightly, but not irreversibly, bound.

Protein binding

~75%

Metabolism

Hepatic. Cytochrome P450 isoenzymes of the CYP3A subfamily facilitate the metabolism of vincristine.

Route of elimination

The liver is the major excretory organ in humans and animals. 80% of an injected dose of vincristine sulfate is excreted via feces. 10 - 20% is excreted via urine.

Half life

When intravenously injected into cancer patients, a triphasic serum decay patten was observed. The initial, middle, and terminal half-lives are 5 minutes, 2.3 hours, 85 hours respectively. The range of the terminal half-life is humans is 19 - 155 hours.

Clearance

Not Available

Toxicity

IVN-RAT LD50 1300 mg/kg; IPR-MUS LD50 5.2 mg/kg. Marqibo® must only be administered IV because it is fatal if administered by other routes. Marqibo® also has different dosing than vincristine sulphate injection, so attention is needed to prevent overdoses. The most clinically significant adverse effect of vincristine is neurotoxicity.

Taxonomy

Description

This compound belongs to the class of organic compounds known as vinca alkaloids. These are alkaloids with a dimeric chemical structure composed of an indole nucleus (catharanthine), and a dihydroindole nucleus (vindoline), joined together.